Merge pull request #80231 from xgerman/patch-1

Update network-rules.md

Author: ktoliver

articles/managed-instance-apache-cassandra/network-rules.md

@@ -50,6 +50,10 @@ If you are not using Azure Firewall, the required network rules and IP address d
 |login.microsoftonline.com:443</br> Or</br> [ServiceTag](../virtual-network/service-tags-overview.md#available-service-tags) - Azure AD | HTTPS | 443 | Required for Azure Active Directory authentication.|
 | packages.microsoft.com | HTTPS | 443 | Required for updates to Azure security scanner definition and signatures |
 
+### DNS access
+
+The system uses DNS names to reach the Azure services described in this article so that it can use load balancers. Therefore, the virtual network must run a DNS server that can resolve those adresses. The virtual machines in the virtual network honor the name server that is communicated through the DHCP protocol. In most cases, Azure automatically sets up a DNS server for the virtual network. If this doesn't occur in your scenario, the DNS names that are described in this article are a good guide to get started. 
+
 ## Managed Instance for Apache Cassandra internal port usage
 
 The following ports are only accessible within the VNET (or peered vnets./express routes). Managed Instance for Apache Cassandra instances do not have a public IP and should not be made accessible on the Internet.
@@ -69,4 +73,4 @@ The following ports are only accessible within the VNET (or peered vnets./expres
 In this article, you learned about network rules to properly manage the service. Learn more about Azure Managed Instance for Apache Cassandra with the following articles:
 
 * [Overview of Azure Managed Instance for Apache Cassandra](introduction.md)
-* [Manage Azure Managed Instance for Apache Cassandra resources using Azure CLI](manage-resources-cli.md)
+* [Manage Azure Managed Instance for Apache Cassandra resources using Azure CLI](manage-resources-cli.md)